Independent fit tool

Six measurements · Eight sizing systems · Private in-browser calculation

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Cup-sized fit plus activity support

Sports Bra Size Calculator for Low, Medium and High Impact

Start with your everyday band and cup size, then match the construction and fit checks to the movement level of your activity.

Size plus motion control34B example

Find a sports bra size and support starting point

Activity impact
High-impact support

Start with 34B US in cup-sized sports bras

Support constructionEncapsulation plus compression

Choose support from the design, not by deliberately shrinking the size.

Alpha-size guidanceUse the specific brand chart

S/M/L and alpha-plus-cup ranges are not standardized between sports brands.

  • A level underband that stays in place when you raise your arms
  • Adjustable straps and a firm, adjustable underband
  • Structured cups or a hybrid design that controls each breast separately

Band alternatives: 32C for a firmer band, or 36A for a roomier band. Use the sister-size calculator before changing band and cup together.

This is a cup-sized starting point, not a universal brand conversion. Test bounce, band movement and breathing comfort in the motions you actually perform. US cup lettering is inconsistent above DD, so confirm the individual brand's sequence.

Should a sports bra be the same size as an everyday bra?

For cup-sized sports bras, begin with the same current band and cup label. A smaller size can restrict breathing without providing the structured motion control that a well-designed sports bra should supply.

How to convert a bra size to an S, M or L sports bra

There is no universal alpha-size conversion. Some brands group several band and cup sizes under one letter, while others offer separate cup ranges such as S (A-C) and S (D-E). Use the result above as your cup-sized reference, then find that exact band/cup combination in the specific brand chart.

How activity impact changes sports bra support

Low-impact activities may work with light compression or encapsulation. Repeated running and jumping usually benefit from structured cups, an adjustable underband and a hybrid design that combines encapsulation with compression.

How to test a sports bra before a workout

Raise both arms, take several deep breaths and repeat the highest-impact movement you expect to perform. The band should stay level, the neckline should contain tissue without cutting in, and the straps should remain secure without carrying all the support.